Australian intelligence determined China was responsible for a cyber-attack on its national parliament and three largest political parties before the general election in May, five people with direct knowledge of the matter told Reuters. The five sources declined to be identified due to the sensitivity of the issue. Reuters has not reviewed the classified report.

The report, which also included input from the Department of Foreign Affairs, recommended keeping the findings secret in order to avoid disrupting trade relations with Beijing, two of the people said.

Australia in February revealed hackers had breached the network of the Australian national parliament. When the hack was discovered, Australian lawmakers and their staff were told by the Speaker of the House of Representatives and the President of the Senate to urgently change their passwords, according to a parliamentary statement at the time. The ASD investigation quickly established that the hackers had also accessed the networks of the ruling Liberal Party, its coalition partner the rural-based Nationals, and the opposition Labor party.

The attackers used sophisticated techniques to try to conceal their access and their identity. The findings were also shared with at least two allies, the United States and the United Kingdom. The UK sent a small team of cyber experts to Canberra to help investigate the attack.

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